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2002

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Articles 1 - 30 of 72

Full-Text Articles in Mechanical Engineering

Acoustical Characterization And Parameter Optimization Of Polymeric Noise Control Materials, Emile N. Homsi Dec 2002

Acoustical Characterization And Parameter Optimization Of Polymeric Noise Control Materials, Emile N. Homsi

Dissertations

The sound transmission loss (STL) characteristics of polymer-based materials are considered. Analytical models that predict, characterize and optimize the STL of polymeric materials, with respect to physical parameters that affect performance, are developed for single layer panel configuration and adapted for layered panel construction with homogenous core. An optimum set of material parameters is selected and translated into practical applications for validation.

Sound attenuating thermoplastic materials designed to be used as barrier systems in the automotive and consumer industries have certain acoustical characteristics that vary in function of the stiffness and density of the selected material. The validity and applicability ...


Evaporating Crossflow Sprays In Gas-Solid Flows, Guangliang Liu Dec 2002

Evaporating Crossflow Sprays In Gas-Solid Flows, Guangliang Liu

Dissertations

Injection of evaporating sprays into gas-solid flows is encountered in many engineering processes such as energy production industry and chemical industry. The phenomenon involves phase change, three-phase interactions, heat and mass transfer. All of these characteristics control the process efficiency, pollutant production and product quality. However, very limited studies are available on the evaporating spray jets in gas-solid flows, especially on the spray evaporation rate within a gas-solid medium. A combined study of experiments and theoretical analysis has been carried out here to investigate the fundamental mechanism of evaporating Crossflow spray jets in gas-solid flows.

In this study, in addition ...


Implementation Of A Two-Dimensional Discrete Element Method To Describe Granular Materials Composed Of Elliptical Cohesionless Particles, Juan Jose Martinez Alvez Dec 2002

Implementation Of A Two-Dimensional Discrete Element Method To Describe Granular Materials Composed Of Elliptical Cohesionless Particles, Juan Jose Martinez Alvez

Theses

This work is aimed at developing a discrete element simulation that models the contact between elliptical grains or particles in granular materials. The goal is to implement an algorithm to carry out collision detection between ellipses as well as ellipsoidal objects. The practical issue here is that the real shape of macroscopic grains can be approximated better using elliptical curves than using spherical curves. In addition, the simulation model will also be valid for spheres, since these objects are special cases of ellipsoids.

An accurate contact detection algorithm was investigated by means of two different formulations. The first formulation determines ...


Computer Simulation Of Automotive Disc Brake Noise, Vadims Milovs Dec 2002

Computer Simulation Of Automotive Disc Brake Noise, Vadims Milovs

Theses

Disc brake noise continues to be a major concern throughout the automotive industry despite efforts to reduce its occurrence. Many articles are written on this subject, but there still is no agreement on what exactly causes disc brake noise and what part of the braking system is responsible for it.

The goal of current research was to build a simplified but inclusive mathematical model of a disc brake system and investigate it using Matlab software. The twodimensional model including damping, Stribeck effect and stick-slip friction was built.

The model is unique in a way that all the similar models have ...


Numerical Study Of Pneumatic Conveying Of Powders, Muhammad Mushahid Rafique Quereshi Dec 2002

Numerical Study Of Pneumatic Conveying Of Powders, Muhammad Mushahid Rafique Quereshi

Theses

The dense phase mode may be advantageous over the dilute phase mode, for some pneumatic conveying problems, because it causes less erosion of the pipeline, less attrition of the material, requires less dust collection and is effective even for smaller pipe diameters. The objective of this study is to numerically determine the parameters that govern the formation slugs in dense phase conveying. The distributed Lagrange multiplier/fictitious domain method (Glowinski et al. 1998 and Singh et al. 2000) is used to perform direct simulations of the motion of solid and gas phases in pipes with rectangular cross-sections. In this approach ...


Electrohydrodynamical Manipulation Of Particles Based On Dielectrophoresis, Oleksii Vasylyschuk Dec 2002

Electrohydrodynamical Manipulation Of Particles Based On Dielectrophoresis, Oleksii Vasylyschuk

Theses

The movement of matter in a non-uniform electric field, termed dielectrophoresis, is of interest to scientists of various branches: physics, chemistry, engineering, and life science. To chemists and physicists it is a science of many varied phenomena. To engineers it is a source of new and useful techniques for separating materials or improving materials’ behavior. To ecologists it provides a major means of minimizing pollution. To life scientists it offers new ways to study and manipulate cells and their subparticles, and to help unravel the nature of living systems.

The purpose of this thesis is to concentrate on some aspects ...


Numerical And Experimental Investigation Of Dry Particle Coating, Ajit Mujumdar Dec 2002

Numerical And Experimental Investigation Of Dry Particle Coating, Ajit Mujumdar

Dissertations

Dry particle coating is an emerging field in the industries that deal with particulate products and powder processing. Compared to the widely reported experimental studies of the dry particle coating, the theoretical modeling of such processes is found to be less comprehensive. The work presented in this thesis is an attempt to fill this gap.

The first part of the dissertation aims at the numerical investigation of the hybridization system (Nara Machinery, Tokyo, Japan). The flow behavior of different materials processed in this device is analyzed using three-dimensional Discrete Element Method (DEM) as well as the computational fluid dynamics (CFD ...


Scale Model Investigations Of The Effects Of Flow Conditioning Devices, Grady P. Saunders Dec 2002

Scale Model Investigations Of The Effects Of Flow Conditioning Devices, Grady P. Saunders

Masters Theses

A scale model was constructed of a portion of a supersonic wind tunnel to perform experiments on various flow conditioning devices. The various devices researched were: swirl vanes, screens, honeycombs, and various combinations thereof. Each flow conditioning device was analyzed to show its effect on total pressure profiles, static pressure profiles, test section flow angularity, test section turbulence, and acoustic noise. Of most concern are the effects flow conditioning devices have on temporal fluctuation of previously mentioned parameters.

The data from these experiments were used as the basis for selecting a screen-honeycomb combination to be installed in the full-scale tunnel ...


Discrete Event Simulation In Manufacturing Environments: The Waste Isolation Pilot Plant, Benjamin Thomas Burnette Dec 2002

Discrete Event Simulation In Manufacturing Environments: The Waste Isolation Pilot Plant, Benjamin Thomas Burnette

Masters Theses

The purpose of this thesis was to construct a discrete event model of the waste handling activities inside of the Waste Isolation Pilot Plant (WIPP) in order to examine "what-if" scenarios designed to increase the rate at which waste is disposed.

The discrete event modeling software EXTEND was chosen by Sandia National Laboratories (Sandia) because of its ease of use, flexibility, ability to customize, and low cost. Historical and observed data were used to construct, verify, and validate the resulting model. Verification ensures that the model works as programmed, and validation ensures the real world system is truly being modeled ...


Development Of A Simulation For The Prediction Of Pvdf Surface Velocity Sensor Response For Vibrating Beams And Rectangular Plates, Brian C. Zellers Dec 2002

Development Of A Simulation For The Prediction Of Pvdf Surface Velocity Sensor Response For Vibrating Beams And Rectangular Plates, Brian C. Zellers

Master's Theses

A simulation for the prediction of Polyvinylidene Flouride (or PVDF) sensor charge response to structural vibration displacements of beam and rectangular plate structures was developed. The simulation uses measured vibration displacements from an actual structure using point sensors (accelerometers) assembled in an array on the surface of the structure. The PVDF sensor charge output equation was written for a PVDF film of constant spatial sensitivity so that numerical analysis tools in Matlab® can be used to solve the equation. Preliminary experimental results showed that the bending strain component, due to transverse vibration displacements, is the dominant term for both the ...


Resonance Detection And Acoustic Behaviour In Polymer Intake Manifolds, Amrith Ramanan Dec 2002

Resonance Detection And Acoustic Behaviour In Polymer Intake Manifolds, Amrith Ramanan

Master's Theses

The Automotive Industry, over the last few years, has been placing major emphasis on the use of lightweight components in engines as well as other structural components. The material for these lightweight components are being chosen in such a way that they require minimal secondary operations to place the components in service. One area that has developed is the use of Polymer (Plastic) Intake Manifolds for Internal Combustion engines. Plastics meet all the criteria for quality low cost production with a minimum weight component. Plastic intake manifolds, however, have been found to be excessively noisy in operation. This noise can ...


Using The Boundary Element Method For Prediction Of Sound Radiated From An Arbitrarily Shaped Vibrating Body, Mark J. Christensen Dec 2002

Using The Boundary Element Method For Prediction Of Sound Radiated From An Arbitrarily Shaped Vibrating Body, Mark J. Christensen

Master's Theses

The Boundary Element Method can be used to predict sound pressure levels radiated from an arbitrarily shaped vibrating body. Using the Direct, Indirect and Approximation formulation one can solve such an ‘exterior’ acoustic problem. In this work, the Direct formulation was chosen. The two major methods employed for implementation of this formulation are the Combined Helmholtz Integral Equation Formulation (CHIEF) and the Burton–Miller Method. Since the CHIEF method was easier to program and adapt to changes, it was decided that the CHIEF method would be the focus of this research. Using the CHIEF method as a guide, a computer ...


Development And Design Of Constant-Force Mechanisms, Brent Lewis Weight Nov 2002

Development And Design Of Constant-Force Mechanisms, Brent Lewis Weight

Theses and Dissertations

This thesis adds to the knowledge base of constant-force mechanisms (CFMs). It begins by reviewing past work done in the area of CFMs and then develops new nondimensionalized parameters that are used to simplify the calculations required to design a CFM. Comparison techniques are then developed that utilize these non-dimensionalized parameters to compare mechanisms based on stiffnesses, percent constant-force, actual lengths, normal displacements, and feasible design orientations. These comparison techniques are then combined with optimization to define new mechanisms with improved performance and range of capabilities. This thesis also outlines a design process, methods to identify mechanisms that are suitable ...


The Evolution Of The Long Term Performance Of Fiber Reinforced Composites Materials Based On Vinyl Easter Resin, Nasser Abdullah Ali-Al Ghailani Sep 2002

The Evolution Of The Long Term Performance Of Fiber Reinforced Composites Materials Based On Vinyl Easter Resin, Nasser Abdullah Ali-Al Ghailani

Theses

Fiber reinforced polymer (plastic) FRP composites are different from traditional

structural materials such as steel or aluminum since the an-isotropic nature of a Fiber _ reinforced composite material creates a unique opportunity of tailoring its properties according to the design requirements. With the accelerated change in the technological sphere, FRP composite materials

have taken a paramount importance in various structural applications, where they successfully replaced conventional materials such as steel. Such success is based on the advantages offered by composite materials such as a high strength to weight ratio. However one aspect that is still delaying full acceptance of these ...


Atomic Force Microscopy Used To Determine The Young's Modulus Of Vascular Smooth Muscle Cells, Samuel C. Lieber Aug 2002

Atomic Force Microscopy Used To Determine The Young's Modulus Of Vascular Smooth Muscle Cells, Samuel C. Lieber

Theses

The Young's modulus of cultured mouse and rat vascular smooth muscle cells (VSMC) was measured with an atomic force microscope (AFM). The AFM can image the three-dimensional structure of biological cells in a physiological environment enabling real-time biochemical and physiological processes to be monitored at a resolution similar to that obtained for the electron microscope (EM). Cellular mechanical properties were determined by indenting the cell's body, and analyzing the indentation data with classical infinitesimal strain theory. This calculation was accomplished by modeling the AFM probe as a cone. as well as a blunted cone. The blunted cone geometry ...


Modeling And Simulation Of The Chemical Etching Process In Niobium Cavities, Qin Xue Aug 2002

Modeling And Simulation Of The Chemical Etching Process In Niobium Cavities, Qin Xue

UNLV Theses, Dissertations, Professional Papers, and Capstones

Niobium Cavities are important parts of the integrated NC/SC high-power linear accelerator (linac) that can accelerate over 100 mA of protons to several GeV. Surface finish of the niobium cavity plays an important role of achieving the best performance of niobium cavity. The chemical etching techniques have been widely used.

Chemical etching of the inner surface of the cavity is achieved by circulating acid through it. The acid interacts with the surface and eliminates imperfections. During the etching process, a pipe with baffles is inserted within the cavity to direct the flow along the surfaces.

A 2-D, axisymmetric, steady ...


Design And Analysis For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Xiaolong Wu Aug 2002

Design And Analysis For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Xiaolong Wu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Fundamental issues related to the selection of a metallic fuel casting furnace design are presented and discussed including heating mechanisms, casting issues, crucible design, and issues related to the mass transport of americium. The process of evaluating all of these different criteria is undertaken to select a concept that would have the greatest chance of success for casting americium in a metallic fuel rod. Based on this evaluation process, a concept for the casting of metallic fuel pins containing high vapor pressure materials is selected and discussed. The important physics of this concept include mass transport of americium from the ...


Heat Release Analysis And Modeling For A Common-Rail Diesel Engine, M. Rajkumar Aug 2002

Heat Release Analysis And Modeling For A Common-Rail Diesel Engine, M. Rajkumar

Masters Theses

The main purpose of this study was to perform a heat release analysis in order to formulate a heat-release model for a common-rail diesel engine. The fundamental idea of the model is to describe the observed physical processes with empirical formulas based on the experimental data.

A Fiat 2.4Liter common rail engine was used in the tests. A rotary incremental encoder with 0.1° resolution was coupled to the crankshaft pulley with a special adapter. The engine was operated at a number of different speeds and load conditions. Cylinder pressure data was recorded using a high-speed data acquisition system ...


Determination Of The Performance Of A Prototype Turbx Engine, Kurt Erickson Aug 2002

Determination Of The Performance Of A Prototype Turbx Engine, Kurt Erickson

Masters Theses

The purpose of this study was to develop a testing procedure to measure the performance of a prototype TurbX. engine. Dr. Michael A. Wilson invented a new concept internal combustion engine called TurbX. and it is said to have higher efficiency and fuel economy compared to other engines. Theoretically, the TurbX. engine cycle can be ideally represented by the Atkinson thermodynamic cycle with a continuous combustion process.

Oak Ridge National Laboratory and The University of Tennessee, Knoxville joined together to conduct tests to determine the performance of the TurbX. engine. A total of 26 fired test runs were conducted to ...


Correlation And Prediction Of Fatigue Crack Growth Rate For Different R-Ratios, Sudip Dinda Aug 2002

Correlation And Prediction Of Fatigue Crack Growth Rate For Different R-Ratios, Sudip Dinda

Master's Theses

The prediction of fatigue crack growth rate of a structural material is an important aspect by which we can predict the critical or safe crack length and, therefore, avoid the sudden failure of components and structures.

There are numerous models which claim to predict the fatigue crack growth rate, but with the exception of the highly published "crack closure methodology" no other model lived up to the expectation of correlating the fatigue crack growth data or predicting the fatigue crack growth rate for different R-ratios.

In order to find an effective solution to the above problem a study has been ...


A Conceptual Design Tool For Engineers: An Amalgamation Of Theory Of Constraints, Theory Of Inventive Problem Solving And Logic, Stephen R. Luke Jul 2002

A Conceptual Design Tool For Engineers: An Amalgamation Of Theory Of Constraints, Theory Of Inventive Problem Solving And Logic, Stephen R. Luke

Mechanical & Aerospace Engineering Theses & Dissertations

This research creates a design methodology by synthesizing three different design tools, the Theory of Inventive Problem Solving (TRIZ), the Theory of Constraints (TOC) and Logic. The basic approach of this design method is to: (1) Reduce a design problem to a logic diagram, (2) Code the inputs and outputs to determine desirability and degree of control, (3) Identify the best inputs to manipulate in order to obtain the desired outputs and (4) Exploit innovative algorithms developed in TRIZ to find the best ways to manipulate the chosen inputs.

This research integrates and expands the methods of TRIZ and TOC ...


Investigation Of Port Fuel Injector Spray Mass Distribution By Laser Induced Fluorescence, Tuba Bayraktar Jul 2002

Investigation Of Port Fuel Injector Spray Mass Distribution By Laser Induced Fluorescence, Tuba Bayraktar

Mechanical & Aerospace Engineering Theses & Dissertations

Modern internal combustion engines have stringent requirements for performance and reduced toxic emissions. The fuel delivery system, and particularly the fuel injectors, have a vital role in reducing unburned hydrocarbons (HC) and carbon monoxide (CO) in exhaust emission.

The main goal of this study is to map the spatial and temporal distribution of the spray from a low-pressure gasoline fuel injector. To attain this goal, three tasks were performed: (1) the experimental investigation of the spray oscillation as functions of operating pressure and injector timing, (2) the determination of the appropriate dye/fuel combinations for one particular experimental technique, and ...


Development Of Icejet-Based Surface Processing Technology, Dimitri V. Shishkin May 2002

Development Of Icejet-Based Surface Processing Technology, Dimitri V. Shishkin

Dissertations

The objective of the proposed work is to acquire knowledge needed for the development and deployment of manufacturing processes utilizing the enormous technological potential of water ice. Material removal by blasting with ice media such as particles, pellets and slugs was investigated. The ice media was accelerated by entrainment in a fluid stream (air, steam, liquid water, supercritical C02), impact of rotating blades, fluid expansion, etc. The ice-airjet has to replace sand blasting and the ice-waterjet has to replace the abrasive waterjet. Based on these results, technical approaches for surface processing and machining will be improved. A primary advantage ...


Destructive Disassembly Of Bolts And Screws Using Impact, Kyung Geun Pak May 2002

Destructive Disassembly Of Bolts And Screws Using Impact, Kyung Geun Pak

Dissertations

Disassembly, the process of separating parts or components at the end of their useful life is complex due to a variety of fastener shapes and variability in their damage during use. As a natural solution, mechanical impact has been suggested as a cost-effective method for destructive disassembly of joining elements.

The objective of this research is to improve the efficiency of impact disassembly process by studying the characteristics of elastic waves caused by impact. This research presents a new method for increasing the shear stress applied on the bolt head without increasing the energy input invested on launching striker. The ...


Concurrent Evaporating Spray Jets In Dilute Gas-Solid Pipe Flows, Xiaohua Wang May 2002

Concurrent Evaporating Spray Jets In Dilute Gas-Solid Pipe Flows, Xiaohua Wang

Dissertations

Evaporating spray jets into gas-solids suspensions are encountered in many industrial applications. The rapid evaporation of spray jets has significant effects on the gas-solids mixing near the jet nozzle regions, including non-uniform solids concentration dilution, gas/solids temperature reduction, and gas/solids velocity acceleration. Furthermore, the jet structure is altered by the change of solids loading, jet mass flow rate and initial droplet size distribution. These interactions of gas, solids and evaporating droplets dominate the process efficiency and product quality. There is an urgent need for exploring fundamental mechanisms of the multi-phase interactions with heat and mass transfer as there ...


Experiments With A Galton Board, Christopher Oshman May 2002

Experiments With A Galton Board, Christopher Oshman

Theses

Galton boards have been used for over a half-century as a tool to illustrate the formation of Gaussian shaped distributions as well as the Central Limit Theorem. Here, the Galton board was used to study the spontaneous percolation of a particle through an ordered array of rigid scatterers. The apparatus that was designed and fabricated provided a means to release 1/8" diameter spheres one at a time in a controlled and precise manner at any location on the board. The three experimental variables used in these experiments were the particle material, the release height, and the board tilt. angle ...


Elasticity In Microstructure Sensitive Design Through The Use Of Hill Bounds, Benjamin L. Henrie May 2002

Elasticity In Microstructure Sensitive Design Through The Use Of Hill Bounds, Benjamin L. Henrie

Theses and Dissertations

In engineering, materials are often assumed to be homogeneous and isotropic; in actuality, material properties do change with sample direction and location. This variation is due to the anisotropy of the individual grains and their spatial distribution in the material. Currently there is a lack of communication between the design engineer, material scientist, and processor for solving multi-objective/constrained designs. If communication existed between these groups then materials could be designed for applications, instead of the reverse. Microstructure sensitive design introduces a common language, a spectral representation, where both design properties and microstructures are expressed.

Using Hill bounds, effective elastic ...


Current Requirements By Electro Hydrodynamic Filter Systems Under Shipboard Operation Conditions, Ravi Shankar Attri May 2002

Current Requirements By Electro Hydrodynamic Filter Systems Under Shipboard Operation Conditions, Ravi Shankar Attri

Theses

An experimental study was performed to determine the current required by an ElectroHydrodynamic (EHD) filter system to clean contaminants from Diesel Engine Lubrication Oil under normal shipboard operation conditions. The amount of current at a set predetermined voltage, which together means Power, was needed in order to anticipate the power required to perform a Shipboard Site Test Evaluation of the EHD filter.

The filter uses the effect of dielectrophoresis to separate contaminants from the lubrication oil. The filter operates at two thousand volts (2KV ac-rms) and thus requires substantial current to energize its electrodes. This type of Power is not ...


Flexible Manufacturing System Utilizing Computer Integrated Control And Modeling, Yahia Mohammed Al-Smadi May 2002

Flexible Manufacturing System Utilizing Computer Integrated Control And Modeling, Yahia Mohammed Al-Smadi

Theses

In today's fast-automated production, Flexible Manufacturing Systems (FMS) play a very important role by processing a variety of different types of workpieces simultaneously. This study provides valuable information about existing FMS workcells and brings to light a unique concept called Programmable Automation.

Another integrated concept of programmable automation that is discussed is the use of two feasibility approaches towards modeling and controlling FMS operations; the most commonly used is programmable logic controllers (PLC), and the other one, which has not yet implemented in many industrial applications is Petri Net controllers (PN). This latter method is a unique powerful technique ...


An Experimental And Numerical Study Of Open Cavity Flows, Sekhar Radhakrishnan May 2002

An Experimental And Numerical Study Of Open Cavity Flows, Sekhar Radhakrishnan

Doctoral Dissertations

This work is part of an ongoing study aimed at understanding of cavity flow oscillations. An experimental setup was designed, constructed, and tested to measure the Sound Pressure Levels (SPL) on the floor of four cavities, and to quantitatively visualize the flow-field inside the cavity. Measurements were made for a fixed cavity width by depth ratio of 3.33, for four length by depth (L/D) ratios of 2.0, 2.5, 3.5 and 4.5. Using Particle Image Velocimetry (PIV), the cavity velocity fields were obtained at subsonic speeds ranging from Mach 0.3 to Mach 0.6 ...